DESCRIPTION Esophageal cancer is one of the most common cancers worldwide with a well-demonstrated variation in its incidence among different populations. Exposure to environmental carcinogens is believed to be a major causative factor for human esophageal cancer and cytochrome P450 plays a key role in the metabolic activation of most environmental carcinogens. In this proposal the investigators will investigate the relationship between CYP2E1 polymorphisms and esophageal cancer risk. First, they will look for an association between genotypes at the CYP2E1 locus and esophageal cancer using patients and their matched non-cancer controls. They will also look for an interaction between genotypes at CYP2E1 and the glutathione S-transferase M1 (GSTM1) locus on cancer risk. Second, they will look for correlations between the CYP2E1 genotypes and phenotypic expression in non-cancerous esophageal samples. The expression of CYP2E1 will be determined by immunohistochemical analysis.